Are these Simon sibsets useable?

Simon is one of my new favorite names, and I am just mulling over potential brothers. Two of my other recent favorite names are Calvin and Theodore. Are these sibsets at all useable?? I just need some outside opinions because I have been thinking about this for too long that I don't know if I trust my judgement anymore. Thanks!

I think they are both useable; however, Simon and Calvin sounds more twinsy than Simon and Theodore, since they end in the same consonant. For some reason, Simon and Theodore seem to be more of the same genre, but I don't think Simon and Calvin are too far off either, like if you had Simon and something very modern and American (I think of Simon as a name with a British flair)...